The present invention relates to sealed packages. More specifically, the present invention relates to plastic bags filled with fine particulate matter, such as flour.
It is highly desirable to reduce the amount of air inside a package containing particulate matter. Air removal helps preserve the product and reduces the volume occupied by the package, thereby reducing the space required for shipping.
Plastic bags containing fine particulate matter are disclosed in U.S. Pat. No. 6,120,817 entitled “Container for Storing Fine Particles.” The disclosed plastic bags have one or more macroscopic apertures or openings for exhausting entrapped air without loss of particulate matter when the bag is squeezed. This is accomplished by covering the apertures with layers of air-permeable, particulate-impermeable material that are attached to a surface of the bag.
U.S. Pat. No. 6,101,685 discloses plastic bags containing fine particulate matter and having a multiplicity of microscopic pores of a sufficient dimension to permit air to escape therethrough while preventing fine particles from escaping when the bag is squeezed. The microscopic pores can be formed using lasers before or after the bag is filled.
One known pouch for flour product has both panels laser perforated near the top and near the bottom. The employment of laser perforation increases the cost of the package.
There is a need for a resealable package that can be squeezed to remove entrapped air without loss of powder product and that can be manufactured at relatively low cost.